A typical internal combustion engine includes a cylinder block, a cylinder head attached to the block, one or more pistons, and one or more combustion chambers. The cylinder block has at least one cylinder bore containing a cylinder liner, and each piston is slidably positioned within each cylinder liner. The cylinder head has a body, and the body, the piston, and the cylinder liner define the combustion chamber.
A typical cylinder head for an internal combustion engine is formed by a casting process and has an inner wall, an outer wall, and sidewalls. The cylinder head is designed to control gaseous flow from intake manifolds in the cylinder head to the combustion chamber and from the combustion chamber to exhaust manifolds in the cylinder head. The cylinder head may have three regions, commonly referred to as an upper deck, a middle deck, and a lower deck. The lower deck is mounted to the cylinder block adjacent to, and partially defining, one or more of the combustion chambers. Generally, the gaseous flow passes through the lower deck of the cylinder head. If required, the cylinder head may support a fuel injector and a firing mechanism for each combustion chamber of the internal combustion engine. Because each of these requires openings to the combustion chamber through the lower deck, there are areas on the lower deck subject to increased levels of heat and stress that develop during the combustion process.
As a result of the operation of the internal combustion engine, the combustion chamber, cylinder head, and piston, as well as other areas of the cylinder block are exposed to high levels of heat. The heat creates thermal gradients through the engine that result from heat of the combustion process and a cooling system process. The thermal gradients can create localized stress regions and hot spots within the lower deck of the cylinder head that have the potential to alter the alignment of the valves, the fuel injector, the firing mechanism, and other components in the engine, which can cause the engine to operate in a less than ideal manner. In addition, with the lower deck of the cylinder head experiencing these stresses, the lower deck has the potential to deform or crack.
Generally, fluid flow paths have been provided in the cylinder head to draw heat from the hot spots. The use of the flow paths as cooling fluid passageways assists in maintaining the cylinder head near a uniform temperature and reduces the likelihood of fracturing as the cylinder head temperature fluctuates. U.S. Pat. No. 4,690,104 (“Yasukawa”) describes one such type of cylinder head. Yasukawa is directed to a cylinder head that provides plugs to speed up coolant flow in regions of large cross-sectional areas. In addition, Yasukawa provides several fins located on boss portions for securing the cylinder head to the cylinder block, as well as on cylindrical walls that connect the intake and exhaust valves to the combustion chamber.
One drawback to Yasukawa is that neither the plugs nor the fins provide additional rigidity to the inner walls of the cylinder head. As a result, the inner walls have the potential to experience problems with a lack of stiffness and failure because of the cyclic loadings created by combustion of fuel in the combustion chambers. Additionally, Yasukawa does not provide cooling fluid flow in certain areas of the engine that are likely to have the highest temperatures.
The present disclosure is directed to overcoming one or more of the problems or disadvantages existing in the prior art.